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331.
采用EPAMethod29方法、冷原子吸收光谱法和电感耦合等离子体质谱法采集和分析一台超低排放燃煤机组污泥掺烧前后的原燃料、烟气和副产物样品中各痕量元素浓度,研究污泥掺烧对燃煤电厂痕量元素排放特性的影响.结果表明:污泥中富含Zn、Cu元素,浓度分别是煤样中的18.81倍和17.64倍.污泥掺烧使掺配后入炉煤中痕量元素含量普遍升高.污泥掺烧前后整个系统、锅炉系统和全流程大气污染控制设施的痕量元素质量平衡率均在可接受范围内.污泥掺烧对痕量元素的分布特征无明显影响,随粉煤灰排放是痕量元素的主要排放去向.通过烟囱排放到大气环境的痕量元素排放量占比很小,不超过0.43%.污泥掺烧前后SCR入口烟气中痕量元素除Hg外主要以颗粒态形式存在.污泥掺烧后各痕量元素在粉煤灰和底渣中的相对富集系数未显著改变.经过全流程大气污染控制设施协同控制后,污泥掺烧前后烟囱总排口痕量元素排放浓度分别为0~12.76,0~14.97μg/m3.污泥掺烧后痕量元素排放浓度均满足美国燃煤发电机组有害大气污染物排放标准、上海市燃煤耦合污泥电厂大气污染排放标准和生态环境部生活垃圾焚烧污染控制标准的限值要求.... 相似文献
332.
Protected areas (PAs) are key elements for biodiversity conservation and ecosystem services. Brazil has the largest PA system in the world, covering approximately 220 million ha. This system expanded rapidly in the mid‐1990s to the mid‐2000s. Recent events in Brazil, however, have led to an increase in PA downgrading, downsizing, and degazettement (PADDD). Does this reflect a shift in the country's PA policy? We analyzed the occurrence, frequency, magnitude, type, spatial distribution, and causes of changes in PA boundaries and categories in Brazil. We identified 93 PADDD events from 1981 to 2012. Such events increased in frequency since 2008 and were ascribed primarily to generation and transmission of electricity in Amazonia. In Brazilian parks and reserves, 7.3 million ha were affected by PADDD events, and of these, 5.2 million ha were affected by downsizing or degazetting. Moreover, projects being considered by the Federal Congress may degazette 2.1 million ha of PA in Amazonia alone. Relaxing the protection status of existing PAs is proving to be politically easy in Brazil, and the recent increase in frequency and extension of PADDD reflects a change in governmental policy. By taking advantage of chronic deficiencies in financial and personnel resources and surveillance, disputes over land tenure, and the slowness of the Brazilian justice, government agencies have been implementing PADDD without consultation of civil society. If parks and reserves are to maintain their integrity, there will need to be investments in Brazilian PAs and a better understanding of the benefits PAs provide. Degradación, Reajuste, Eliminacióm de las Listas y Reclasificación de Áreas Protegidas en Brasil 相似文献
333.
采用田间试验方法,进行了生物稻壳粉、生物稻草粉2种生物有机除草剂对水田杂草的防效试验。结果表明,2种生物有机除草剂对水田杂草均有不同程度的防效,其中生物稻壳粉防效最好、经济效益最高,生物稻草粉防效和经济效益次之。该试验研究为生产有机水稻提供了新的除草方法。 相似文献
334.
采场是煤矿生产的核心地带,而采场通风系统是确保采场作业安全,创造良好生产环境的重要环节。本文以采场风流流动及瓦斯运移理论为基础,通过现场试验、模型模拟试验及计算机模拟研究等方法,着重研究了中国常用的和有发展前途的走向长壁后退式U型通风方式、U+L型通曲方式、后退式Y型通风方式条件下采场风流流动及瓦斯运移规律。 相似文献
335.
MFAM模型在河流水质污染模拟及预测中的应用 总被引:2,自引:0,他引:2
文中以时间序列分析为基础,介绍了均值生成函数这一崭新概念,并且经成份因子提取分析推导建立了模拟序列的数字模型(简记为MFAM),经对黄河下游花园口断面的1988-1989年实测水质污染指标溶解氧(DO),氨氧,化学耗氧量(COD),五日生化需氧量(BOD5)等序列模拟,结果表明MFAM模型能较好地模拟河流水质污染指标的变化趋势,拟合平均误差只有5.2-6.4%,MFAM模型应用于预测1990-1991年水质污染指标变化,结果表明预测精度达85%以上,文中最后得出结论:MFAM模型应用于河流污染模拟和预测,是完全可行且十分方便。 相似文献
336.
本文概述了植物的铁素营养、果材缺铁黄化病的诊断治疗方法,论述了高涌液注射法矫治果树缺铁黄化病的理论、假说、树木微型注射器、克黄灵高渗液、树干穴位注射法、树干穴位插管法及其应用前景。 相似文献
337.
本文以提高光热资源利用率、人工改变秧田微气候条件,提早中稻播期为突破口,辅之以提早移栽期和间种优质懦稻等系列配套技术措施,促成了前季中稻的早熟、高产、早收,同时又为后季再生稻创造了必要的时间和温光条件,从而使水稻单产提高20%以上。 相似文献
338.
建立城市自然灾害承灾能力指标的思路探讨 总被引:10,自引:0,他引:10
本文论述了城市承灾能力的含义,分析了我国城市主要自然灾害以及承文体的类型和致灾因素,探讨了城市承灾能力指标,为城市承灾能力综合评判提供了依据. 相似文献
339.
Peter F. M. McLoughlin 《Journal of the American Water Resources Association》1988,24(3):599-607
ABSTRACT: Third World irrigation and drainage systems have experienced major declines recently in both capability and performance. This is due initially to working them well beyond their design capaci-capacities; scouring, sedimentation, and overtopping result. Chronic O&M underfunding then adds heavily to this worsening malaise. International donors have assisted irrigation departments with rehabilitation projects and programs to improve O&M effectiveness on a grand (billions of dollars) scale. Despite their historical propensity to examine, almost fastidiously, program economic justifications (B/C, IRR, etc), the donors apparently have glossed over two basic analytic elements for (a) more spending on O&M as distinct from an equivalent spending on other means to provide farmers with an m3 of water; and (b) different levels of O&M spending on canals and drains. Surely those different levels provide differing benefits, in total, and at the margin. Which level is most economic? This paper identifies these latter analytical issues, posits methodologies key to an O&M spending level analysis, and discusses the information base. Particular attention is paid to identifying relevant costs and benefits, and to suggesting supplementary criteria for O&M spending level selection. The paper is an exercise in delineation of an imminently practical area of irrigation engineering economics. 相似文献
340.
In many locations, regulatory agencies do not permit tree planting above landfills that are sealed with a capping clay, because
roots might penetrate the clay barrier and expose landfill contents to leaching. We find, however, no empirical or theoretical
basis for this restriction, and instead hypothesize that plant roots of any kind are incapable of penetrating the dense clays
used to seal landfills. As a test, we excavated 30 trees and shrubs, of 12 species, growing over a clay-lined municipal sanitary
landfill on Staten Island, New York. The landfill had been closed for seven years, and featured a very shallow (10 to 30-cm)
soil layer over a 45-cm layer of compacted grey marl (Woodbury series) clay. The test plants had invaded naturally from nearby
forests. All plants examined—including trees as tall as 6 m—had extremely shallow root plates, with deformed tap roots that
grew entirely above and parallel to the clay layer. Only occasional stubby feeder roots were found in the top 1 cm of clay,
and in clay cracks at depths to 6 cm, indicating that the primary impediment to root growth was physical, although both clay
and the overlying soil were highly acidic. These results, if confirmed by experimental research should lead to increased options
for the end use of many closed sanitary landfills. 相似文献